[C++] Support type promotion in basic evolution strategy

Most of the pieces are in place for this. If a fragment has int32 and the dataset schema is int64 for example then the basic evolution strategy should be able to safely cast.

We might even consider supporting unsafe casts like int64 -> int32 if we can detect overflow and raise an error.

**Reporter**: [Weston Pace](https://issues.apache.org/jira/browse/ARROW-17757) / @westonpace

_{**Note**: *This issue was originally created as [ARROW-17757](https://issues.apache.org/jira/browse/ARROW-17757). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

The issue names no files, tests, or entry points. Start by locating the basic evolution strategy and reading the linked migration documentation; done means safely promoting fragment types to the dataset schema, with any unsafe-cast behavior explicitly resolved.

Written by the indexing model from the issue text.